1. Field of the Invention
The invention relates to a packaging structure of image sensors and method for packaging the same, and in particular, to a packaging structure in which a substrate for carrying an image sensing chip is formed using plastic materials and the substrate includes metallic pins, thereby lowering the manufacturing costs.
2. Description of the Related Art
In typical image sensors, in order to achieve the demands for high heat dissipating efficiency and high sealing property, the substrate for carrying the image sensing chip is formed from ceramic materials. A plurality of -shaped pins connected to each other are formed on the top and bottom surfaces of the substrate extending from the periphery thereof. The image sensing chip is placed on the substrate. Then, the image sensing chip is electrically connected to the pins on the top surface of the substrate by a plurality of wirings. Next, a transparent glass is used to cover the image sensing chip to complete the package of the image sensor. Thus, the pins on the bottom surface of the substrate can be electrically connected to the circuit board in the image sensor after packaging.
In the substrate of the image sensor including ceramic materials, it should be noted that both the selection of the components of the ceramic materials and the control of the working temperature are very important in manufacturing processes. If an improper selection or control is made, the substrate may be easily deformed or cracked. Furthermore, since the ceramic substrate cannot be easily cut without any crack, it must be made individually. Therefore, a lot of ceramic substrates cannot be manufactured at the same time, causing the manufacturing costs relatively high.
Moreover, since the pins on the bottom surface of the substrate are used for electrically connecting to the circuit board, the pins have to form a flat contact surface in order not to influence the electrical connection relationship between the substrate and the circuit board. However, the prior art pins are formed into xe2x80x9cxe2x80x9d shapes on the top and bottom surfaces by pressing. As a result, it is not easy to form a plurality of flat pins, thereby influencing the signal transmission in the image sensor.
In addition, the signal transmission distances for the -shaped pins are relatively long. Therefore, the signal transmission between the image sensing chip and the substrate is also influenced.
In order to solve the above problems, it is necessary to provide a packaging structure and method for an image sensor in which the manufacturing costs can be lowered and the signal transmission of the image sensing chip can be improved.
It is therefore an object of the invention to provide a packaging structure and method for an image sensor which can be manufactured in large quantities to lower the manufacturing costs.
Another object of the invention is to provide a packaging structure and method for an image sensor in which the signal transmission distances can be made shorter to perform better signal transmission properties.
To achieve the above objects, a packaging structure of an image sensor includes a substrate, an image sensing chip, a plurality of wirings, and a transparent layer. The substrate includes a plurality of metal sheets, glue for sealing the metal sheets, a first surface, and a second surface. The metal sheets are exposed to the outside via the first surface and the second surface to form first contacts and second contacts, respectively. The image sensing chip is mounted on the substrate. The plurality of bonding pads are formed on the image sensing chip. The plurality of wirings electrically connect the bonding pads of the image sensing chip to the first contacts of the first surface of the substrate, in order to electrically connect the image sensing chip to the substrate. The transparent layer is arranged above the image sensing chip.
Therefore, the second contacts formed on the metal sheets can electrically and smoothly connect to the circuit board. Furthermore, the signal transmission distances between the image sensing chip and the circuit board can be effectively shortened so as to obtain better signal transmission effects. Moreover, since the substrate formed by sealing the metal sheets with the glue can be easily cut, a lot of substrates can be manufactured at the same time by molding so that the manufacturing costs can be lowered.